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As I was riding home from the Corsaro section gathering in Alton last weekend my 350 sport became very loud as I rode up the A3. I was just a mile from home so rode back.

Once home the reason for the noise was obvious, as the castle nut on the front exhaust was sitting on the down pipe near my toes. This was wired when I bought the bike though the other wasn't, I had been regularly checking the other but assumed that all would be well on the wired side. Clearly not as the wire had slid down the pipe too!

Nut is chewed up but I can get it tightened easily, so I assume the threads are fine. I just need to know what I have lost and where to buy replacements as the pipe is very loose now with the castle nut tightened and certainly is not making any seal there either.

Any advice welcomed.

Mike

Probably the two half collets that holds the nut on the pipe. Do you still have the gasket?

Mike.

As Mike says, the half collets. Trouble is they come in about 3 or 4 variations! The shape and dimensions of the flange on the end of the pipe determine which you'll need. If you can post a pic (I never can) or a drawing with dimensions of the pipe it will make things easier.
I may even have some to suit!

Steve Brown wrote:As Mike says, the half collets. Trouble is they come in about 3 or 4 variations! The shape and dimensions of the flange on the end of the pipe determine which you'll need. If you can post a pic (I never can) or a drawing with dimensions of the pipe it will make things easier.
I may even have some to suit!

Thanks Steve I’ll have go at measuring tomorrow.

Mike

Here are the pictures.

I think the gasket is still there, so I think all I need are the 2 half collets.

Right, the flange on the end, how thick is it? Some pipes are thin there, just the pipe itself flared out. Others are around 3mm thick, a collar welded I think to the pipe.
If you can get the thickness of that flange it will help.

With many thanks to George 350 I now have the collets and a fully functioning front exhaust! I now need help to source a pair of half rings that fit the "square" section flange to replace the ones George sent to me today. Any leads on finding replacements welcomed.

Mike

Lockwire the castle nut to a fin on the head. Resist the temptation to heavily tighten the nut, there are stacks of stripped and seized examples out there that are due to overtightening.

Aye Mike,

When re-assembling, apply liberal amounts of copper grease to the components before tightening with a correct diameter 'C' spanner and then lockwiring as suggested by 'BumbleBee'. It should make future dismantling easier and component corrosion or stripped exhaust port threads less likely.

Good health, BillR

You should lock it with the wire after doing some rides and repeating to turn the nuts as much that you can with a hot motor!

All good points already made.
to add
1. Never use the nut to haul badly fitting pipes into the head, sort out the fitting first! The rear footrest/silencer hangars are often bent inwards.
2. Don't use any exhaust sealant on the thread.
3. Remove any hardened deposits from the threads before reassembling. I use a right angled scribe.
4. Make sure the silencers are properly supported - two bolts and a proper bracket at the rear.
5. Tighten each part of the system a little at a time, to find the best position.
Mark

Hi People,

Just noticed this topic, and it brings back memories of my Dart. At least you can get to those nuts on the naked bikes. I had to make special tools for each exhaust stub because the chassis fit was so tight! I've not seen them since so I guess they went with the bike when I sold it, but there should be pics in the files here if anyone is interested.

As regards the advice above about never getting exhaust sealer on the nut threads, I just wanted to share what was a revelation to me some while back. There are now some excellent products for sealing exhausts which far out-perform the dreadful paste/cement of days gone by. I speak of high-temperature silicone sealers, often with copper in them. They resist all temps you find between engine components, though probably not actual flames, and are vibration-proof. Better yet, they are easy to break apart when you need to detach bits. I use them at exhaust ports and for sealing all exhaust pipework these days. Someone had played about with the end caps on the ST4 cans and I could never get new rivets to seal with old-fashioned cement which broke up with heat cycles and vibration, but silicone has lasted for years!

This advice may come under the heading relating to grandmothers and egg-sucking, so apologies if you-all knew this already!

Nick

nickst4 wrote:Hi People,

This advice may come under the heading relating to grandmothers and egg-sucking, so apologies if you-all knew this already!

Nick

No Nick, it's news to me at least. What is the name of the product please? I have sometimes used hi temp silicone sealants around bad exhaust joints but that stuff while successful was really meant as a regular gasket cement.

I use Innotec AS1500.

It is quite expensive and not that easy to get but it is unparalleled in my opinion. Think of it like an extremely durable, extremely high temperature and pressure modern version of copper grease. Does a fabulous job of lubricating and sealing threads and does not wash or burn away over time. I use it on exhaust ports and brakes mainly. It's a bit overkill for other normal greasing applications, especially given the cost!

I can't remember the last time I had an exhaust nut come undone, and I do not need to use wirelock- even on the 501 dart, which is even harder to do up than Nick recalls the 350 being!

Tom's Innotec 1500 stuff looks to be in a different league altogether, and since it appears to be non-setting, I find it difficult to understand how it could stand gas-pressure. The ads say it is primarily a lubricant, not unlike Loctite C5-A Anti-Seize Copper that resists temperatures up to a more-modest 980degrees C, and is also usable on brake pad backs. Is that a fair assessment, Tom?

The stuff I currently use on exhausts is another Loctite product, SI 5990, a copper-coloured silicone cement, available at modest cost from your local friendly Halfords (other suppliers are available!) I know Permatex do something similar.

Nick

PS I wonder how many readers here are scratching their heads over the egg-sucking reference? Or are we all, ahem, mature in years? Aged pensioner that I am, I somehow doubt that my grandmother ever got that friendly with eggs, but the old sayings are still the best!